Method and apparatus for recording pressure



W. F. HENDRY AND C. E. REDDIG.

METHOD AND APPARATUS FOR RECORDING PRESSURE.

APPLICATION FILED DEC. I6, 1919.

1,426,735. PatenteaAug.22,1922.

v 44 7 I lIIII 20 /n VPH f0/S I/W//fam ff Hand/X Char/es E @Hdd/7 Uni-enSTATES PATENT OFFICE.

WILLIAM FERRIS HENDRY, OF NEW YORK, AND CHARLES E. BEDDIG', OFRICHJNION'D` HILL, NEW YORK, ASSIG-NORS TO WESTERN ELECTRIC COMPANY,INCORPORATED OF NEW YORK, N. Y., A CORPORATION 0F NEW YORK.

METHOD AND APPARATUSFOR RECORDING' PRESSURE.

specification of Letters Patent. Patented Aug 22 1922.

Application led December 16, 1919. Serial No. 345,437.

To all whom t may concern:

Be. it known that we, WiLLAM FERRIs HENDRY and CHARLES E. REDDIG,citizens of the United States, residing at New York, in the county oflNew York and State of New York, and at Richmond Hill, Long island, inthe county of Queens and State of New York, respectively, have inventedcertain new and useful improvements in Methods and Apparatus forRecording Pressure, of which the following is a full, clear, concise,and exact description.

This inventionV relates to an improved method and apparatus forrecording pressure which has as its primary object the recording ofpressure by electrically deflecting a beam of light commensurate withthe pressure fluctuations upon a photographic film.

rlhe improved method and apparatus herein is especially adapted forapplication to gas, heat and other engines of this gen-.

eral type. ln the embodiment of the invention in an apparatus, thepressure vto be recorded is directed against a diaphragm, which variesthe current in an electrical circuit which has interposed therein thesuspended mirror of the usual type of oscillograph, the film thereofbeing driven synchronously with the operation of the engine,

the pressure of which is to ybe recorded. Y

Devices heretofore designed for determining the pressures within thecylinders of engines have employed the use of a dia.- phragm whichcaused the physical movement of levers, links, or other suitablemechanism to actuate a recordingr device. In pressure measuringmechanisms where a mirror was utilized, the mirror was moved through theactuationy of physical elements which Ewere under the control of a diaphragm, against which the pressures in the engine cylinder were exerted.In these prior devices, the friction and inertia of the partsnecessarily prevented the making of a complete record which would showall of the slight and minute pressures which occurred within thecylinder of the. engine.A In the method and apparatus for recordingpressure disclosed herein, only a very slight movement is imparted tothe diaphragm by the pressure 'directed thereagainst, which movement,however, is suflicienti to vary the resistance of the carbon piles toelectrically effect a movement ofthe mirror. Since the parts of theapparatus have no appreciable movement, the inertia and friction ofthese parts isveryvslight and, as a result, when the engine is operatingat high speeds, all irregularities of expansion of the gases or similar.occurrences within the cylinder of the engine are truly translated bythe carbon pile resistance and mirror, producing a record which losesalmost no detail due to the inertia or friction of the parts.

The. accompanying drawing shows, in side elevation, and partly insection, apparatus for electrically interpreting pressures andillustrating its connection with a` gasoline engine, and an oscillographwhich are both repreented diagrammatically.

ln the embodiment of the invention illustrated in the drawings, a singlecylinder internal combustion engine 10 .of the usual type has a gear 11mounted on its crank shaft which actuates a pinion 13 through the mediumof 'an intermediate gear 12, the pinion 13 having secured thereto apulley 14 which drives a pulley 16 through the mel diuin of a belt 15,the pulley 16 being secured to the film driving shaft of thephotographic mechanism of an oscillograph illustrated diagrammaticallyat 17. Due'to the gear train comprising the gears 11, 12

and 13, the lm of the oscillograph is driven in synchronism with therotation of the crank shaft and hence also synchronously with themovement of the piston 18 of the engine 10. The mirror 19 of theoscilloance device 2l, the electrical effect of which 'is controlled bythe pressure within the comy bustion chamber 22 of the engine 10 as willbe hereinafter described. The mirror 19 de- Sli rives its movementthrough the varying current in the circuit caused by the resistancedevice 21.

The resistance device 21 comprises a base 23 carrying standards' 24which pass through an intermediate member 25 and sup ort a.

head member 26. which is held in position by;

means of nuts 27 and 28. Three tubes 5, 6

and 7 of hard rubber or other suitable insulating material are supportedat their lower ends upon the base 23 and have their upper ends fittedwithin counter sunk openings 30 made in the intermediate member 25. Nuts31 serve to clamp and firmly hold the tubes 5, 6 and 7 iIi positionbetween the intermediate member 25 and the base 23. Three cylindricalsections of brass 32, 33 and 34 are placed on top of each other in eachof the tubes 5, 6 and 7. The lower end of each of the sections 33 and 34are provided with screw threaded apertures to receive screws 35, theheads of which carry disks of carbon 36. Al disk of insulating material4 is interposed between each lowermost section 32 and the base 23. Eachof the uppermost cylindrical sections 34 are provided with a recess 36to receive a pin 37 formed of insulating material carried by a follower38, which is supported upon the upper cylindrical sections 34 and isprovided with a knob 39 which projects through a vertical passage 40formed in the head member 26 and contacts with a diaphragm 41 supportedupon the lower flange 42 of an annular chamber 43 made in the headmember 26. A hollow screw threaded plug 44 is screwed within a verticalpassage 45 -made in the head portion 26 and has its power end inengagement with the upper surface of the diaphragm 41. The screwthreaded plug 44 is provided with a plurality of openings 46 whichestablish communication between the hollow interior of the plug 44 andthe annular chamber 43 the latter being placed in communication with thecombustion chamber 22 ofthe engine 10 by means of a pipe 47. i

Terminals 48, extend through enlarged openings 49 made in the side ofthe tubes 5, 6 and 7 and are screwed within screw threaded aperturesformed in the uppermost cylindrical sections 34 and lowermostcylindrical sections 32. One side of the battery 20 is connected by aconductor 50 with the terminal 48 which is'secured to the uppermostcylindrical sections 34 within Vthe tube 5. The-terminals 48 attached tothe lowermost cylindrical sections 32 within the tubes 5and 6 areconnected by a conductor 51 and the terminals 48 attached to theuppermost cylindrical sections 34 within the tubes 6 and 7 are connectedby a conductor 52. The terminal 48 secured to the lowermost cylindricalsections 32 within the tube 7 is connected by a conductor 53 with theoscillograph 19 which in turn is connected with the other side of thebattery 20. Due to the arrangement ot' the conductors just described thecylindrical sections 32, 33 and 34 within the tubes 5, 6 and 7 areconnected in series with the oscillograph 19 and baten the `engine 10 isin operation, the

medium of follower 38 upon the cylindrical 70 (sections 32, 33 and 34within each of the insulatin tubes 5, 6 and 7. Due to the presence o thecarbon disks 36 interposed between the cylindrical sections 32, 33 and34 the current in the circuit including these sections. and the battery20 will be varied commensurate with the varying pressures exerted by thediaphragm 39. vThe varying current in the circuit causes the movement ofthe mirror 19 in the usual manner which will refiect a beam of lightfrom the source 2 to produce an irregular line upon the continuouslymoving film within the photographic mechanism 17 of the oscillograph.Since the contour of the line formed upon the film is commensurate withthe varying pressures produced within the combustion chamber 22 of theengine and since the film is driven at a speed commensurate with themovement of the piston of the engine, a film is produced from which thepressures produced within the combustion chamberv 22 of the engine maybe computed.

What is claimed is:

1. A method of recording pressure, consisting in varying-the current inan electrical circuit commensurate with the pressure fluctuations anddelecting a beam of light upon a photographic film commensurate with thevarying current in the circuit.

2. A- pressure recording apparatus com-v prising a pressure actuatedelement, a resistance controlled thereby,- and a circuit including saidresistance and means actuated commensurate with the varying current in105 the circuit for delecting a beam of light upon a photographic film.

3. A pressurerecording apparatus comprising-a pressure actuated element,a resistance device in engagement with said ele- 110 ment, and a circuitincluding said resistance device and means actuated commensurate withthe varying current in the circuit for defiecting a beam of light upon aphotographic film.

4. A pressure recording apparatus for gas and heat engines and the likecomprising a pressure actuated element, a resistance device inengagement with said element, a circuit including said resistance deviceand 120 means actuated commensurate with the varying current in thecircuit for deecting a beam of light upon a photographic film, and meansfor actatin said film in synchroly with the piston o the engine.

pressure recording apparatus conl prising a pressure actuated element, aplurality of resistance devices connected in series andoontrolled\.thereby, and a circuit including said resistance devices andmeans 130 actuated commensurate with the varying current in the circuitfor deflecting a beam of light upon a photographic film. y

6. A pressure recording apparatus comi prising a pressure actuatedelement, a plurality of resistance elements in engagement with saidpressure actuating element, and a circuit including said resistanceelements in series an'd means actuated commensurate with the varyingcurrent in the circuitfor deflecting abeam of light upon a photographicfilm.

7. A pressure actuated element, a member operated thereby, a resistancedevice in engagement with said member, and a circuit. including saidresistance device and means actuated commensurate with the varyingycurrent in the circuit for deflecting a beam of light upon aphotographicfilm.

8.r A pressure recording apparatus comprising a pressure actuatedelement, amem ber vcontrolled thereby, a plurality of resistanceelements in engagement with said member, andra circuit including saidresistance elements and means actuated commensurate with the varyingcurrent in the circuit for deflecting a beam of light upon aphotographic. film.

9. A pressure recording apparatus for gas .and heat engines and the likecomprising a pressure actuated element, a member operated thereby, aresistance element in engagement with said member, a circuit includingsaid resistance and means actuated 'commensurate with the varyingcurrent in the circuit for deflectinga beam of light upon a photographicfilm, and means Jfor actuating the said film in synchrony with thepiston of the engine.

10. A pressure recording apparatus comprising a pressure actuatedelement, a re.- sistance device in engagement therewith and insulatedfrom said element, and a circuit .including said resistance device andmeans actuated commensurate with the varying current in a circuit fordefiecting a beam of light upon a photographic film. I

l1. A pressure recording apparatus comprising a pressure actuatedelement, a mem: ber operated thereby, a pluralityO of resistanceelements in engagement with said .member and insulated therefrom and acircuit including said resistance elements and means actuatedcommensurate with the varying current in the circuit for defiecting albeam of light upon a photographic film.

12. A pressure recording-apparatus comprising a'pressure actuatedelement, a revice comprising a Iseries of superimposed ,f metal andcarbon members, and a circuit including said resistance device and meansactuated commensurate with the varying current in the circuit fordeflecting a beam of light upon a photographic film. l

13. A pressure recording apparatus comprising a pressure actuatedelement, a vresistance device controlled thereby, said device comprisingsuperimposed metal inembers, and a plurality of carbon memberspositioned therebetween, an electrical conductor having its endsconnected to the uppermost and lowermost metal members of the resistancedevice, and a source of electrical energy and recording means connectedin said conductor in series, said recording means actuated commensuratewith the varying current in the conductor for deflecting a beam of lightupon a photographic film.

14. A pressure recordin apparatus for gas and heat engines and t e like,compris- 'ing a pressure actuated element, a resistance device inengagement withsaid element, a circuit including said resistance deviceand means actuated commensurate with the varying current of the circuitfor deflecting a beam of light upon a photographicfilm, and means foractuating said film at a constant speed.

15. A pressure recording apparatus for gas and heat engines and the likecomprising a pressure actuated element, a member operated thereby, aresistance element in engagement with said member, a circuit includingsaid resistance and means actuated commensurate with the varying currentin the circuit for deflecting a beam of light upon a photographicfilm,'and means for actuating said film at a constant speed.

16. A pressure recording apparatus for gas and heat engines and the likecomprising a pressure actuated element, a resistance device controlledthereby, a circuit including said resistance device, record material,means for feeding said record material in synchronism with the piston.of theI engine, and means actuated commensurate with the varying currentfor making a record upon said record material.

In witness whereof, we hereunto subscribe our names this'lOth day ofDecember A. D., 1919.

WILLIAM FERRIS HENDRY. lCHARLES E. REDDIG.

